and SuperNova Remnants • We bid a fond farewell to clusters and start a new topic... supernova and supernova remnants

1

Super and Super Nova Remnants • Types of Super Nova • Explosions • Nucleosynthesis • Physics of Supernova remnants • Particle Acceleration • Cosmology?

Radio images of SN2008 2 in M82 +Size vs time Supernovae and Supernova Remnants

Supernovae • T~ 5000 K effective of photospheric optical emission during early period

• most of photon energy is in the is optical and infrared timescale ~ year create a fair fraction of the elements

3

Supernovae and Supernova Remnants

Supernova remnants powered by expansion energy of supernova ejecta, dissipated as the debris collides with interstellar material or stellar mass loss generating shocks T ~ 106-7 K characteristic thermal emission is X-rays timescale ~100-10,000 years

4 SNR are multi-wavelength objects

•SNR appearance in different energy bands depends on type of SN and the surrounding medium and age –SNR size/morphlogy is not a proxy for age

•X-ray-primary shock physics, thermal content, ISM , ejecta abundances

•Optical- secondary shock physics, and (occasionally) shock speed and abundances

•Radio- particle acceleration

• To understand SNRs as a class, high quality data are required at multiple wavelengths

5

Why Study Supernova/Supernova Remnants? Supernova explosion: How is mass and energy distributed in the ejecta? What was the mechanism of the supernova explosion? What and (how much) elements were formed in the explosion, and how? What are the characteristics of the compact stellar remnant?

6 Why Study Supernova/Supernova Remnants?

Shock physics: How is energy distributed between , ions, and cosmic rays in the shock? How do electrons and ions share energy behind the shock?

7

Why Study Supernova/Supernova Remnants?

Interstellar medium: How is the structure of the interstellar medium affected, and how does the shock interact with that structure?

How is the ISM enriched and ionized- how are the metals created and distributed

8 Supernova- sec 4.1-4.3 of Rosswog and Bruggen • Supernova come in two types (I and II) – Type Ia is the explosion of a pushed over the Chandrasekar limit- details are not well understood • However they are used as a standard candle for cosmology – Type Ib and II is the explosion of a massive after it has

used up its nuclear fuel- massive M>8M¤ star – Type I supernovae do not show in their spectra. Type Ia supernovae reach peak luminosities of about 43 10 4 x10 erg/s (e.g. 10 L¤,MB ~ -19.5 at maximum light,) with very similar light curves • Type II supernovae show hydrogen in their spectra. Their light curves are diverse, with peak luminosities having a wide range ~2x1042-2x1043 erg/s 9

How Massive Explode- T-H Janke

10 • Remember Project ? • Due the week before the last day of classes.. Dec 3 ~10 pages- double spaced- use figures if you want, but not to excess. please cite your references you can use internet resources but must reference them topic of your choice that you are excited about directly related to the class BUT not a topic that we covered in any depth. Original research encouraged but not required

11

SN*types*M*Observa3ons* Optical classifications of SN

• I*–*No*H*in*spectrum* – Ia*:**No*He*either,*but* characteris3c*Si*absorp3on* – Ib:**He,*as*well*as* intermediate*mass* elements,*O,*Mg,*Ca*I* – Ic:*No*He,*but* intermediate*elements* • II*–*Strong*H*in*spectrum* – IIMP*:*plateau*in*light*curve* – IIML:*linear*decline*aTer* maximum* K. Long – IIn:*narrow*mul3ple*H*lines* flux vs wavelength near maximum light for Ia and several core collapse (CC) types 8/21/12* Astro*H*M*Kyoto* 12 3* Type Ias appear in all types of , need several very specific events to push white dwarf over the .

Type II and Ib Because massive stars are short lived these supernovae happen in star forming regions – never in elliptical galaxies Type II events occur during the regular course of a massive stars evolution. (adapted from Type Ia Supernovae and Accretion-Induced Collapse Ryan Hamerly)

13

Types of Supernovae Type Ia Type II • No H, He in spectrum Both H, He in spectrum • No visible progenitor (WD) Supergiant progenitor • Kinetic Energy: 1051 erg Kinetic Energy: 1051 erg • EM Radiation: 1049 erg EM Radiation: 1048-49 erg • Likely no burst ? : 1053 erg • Rate: 1/300 yr in Milky Way Rate: 1/50 yr in Milky Way • Occur in spirals and ellipticals Occur mainly in spiral galaxies • No compact remnant NS or BHs • most of the explosion energy is vast majority of the energy is in in heavy element synthesis neutrino emission and kinetic energy of the ejecta decay of radioactivity keeps it bright for years.

14 Supernova - Summary

• Type Ia •Type II • No hydrogen • Hydrogen in spectrum • Thermonuclear explosion of a white • M > 8 solar masses dwarf • core collapses to a star or • No bound remnant • • ~1051 erg kinetic energy • ~1051 erg kinetic energy • • v ~ 2,000 – 30,000 km s-1 • v ~ 5,000 – 30,000 km s-1 • Neutrino burst ~ 3 x 1053 erg • No neutrino burst 49 • Eoptical ~ 10 erg 49 42 -1~ • Eoptical ~ 10 erg • Lpeak ~ 3 x 10 erg s 3 months(varies 43 from event to event) • Lpeak ~ 10 erg s-1 for 2 weeks • Radioactive tail (56Co) • Radioactive peak and tail (56Ni, 56Co) • 2/100 yr in our • 1/200 yr in our Galaxy • • Makes about 1/3 iron and all the • Makes about 2/3 of the iron in the plus many other elements MilkyWay

15

Two Paths to a SNe

Ia

II

16 The Life of SN1987A- AKA SK-69-202 Progenitor star was a previously catalogued blue supergiant

Mass = 18 M¤

17

How to Get to a Type I • Route to a type I is very complex and not well understood • There maybe several evolutionary paths

SN 18 Supernova Explosions Ia Thermonuclear Runaway • Accreting C-O white dwarf reaches Chandrasekhar mass limit (more when we study NS and BHs), undergoes thermonuclear runaway

• Results in total disruption of progenitor (no remnant NS or BH) • Explosive synthesis of Fe-group plus some intermediate mass elements (e.g., Si)

19

Type Ia Supernova Explosion

Uncertain mechanism and progenitor: probably a delayed detonation* (flame transitions from subsonic to supersonic speed) or deflagration* • Amount of Ni (which drives the long term light curve) synthesized is not the same from object to object èdifferent ejecta mass èdifferent explosion energies èasymmetries in the explosions èdifferences in the explosion physics

*Detonation is the violent reignition of in a white dwarf star . It is a runaway thermonuclear process which spreads through the white dwarf in a of seconds, *Deflagration-"Combustion" that propagates through a gas or across the surface of an explosive at subsonic speeds, driven by the transfer of heat 20

Type Ia's • Why a thermonuclear explosion of a white dwarf? – Kinetic energy of ejecta ~5x1017 erg/gm (~1/2v2~(104km/sec)2) is similar to nuclear burning energy of C/O to Fe (~1 Mev/ nucleon) – lack of remnant (e.g. NS or BH) or progenitor in both pre and post explosion observations. – occur in elliptical galaxies with no star formation • But (Rosswog and Bruggen pg 136) – No consensus on • mass of WD or its composition before explosion • origin of accreted material (either mass from a 'normal' companion or the merger of 2 white dwarfs) • exact explosion mechanism

21

Type Ia- How the Explosion Occurs • Deflagration wave – Deflagration- "Combustion" that propagates through a gas or across the surface of an explosive at subsonic speeds, driven by the transfer of heat. 8 In main sequence stars Tc~ 10 K to ignite core burning- 10 in SNIa Tcore~10 K temperature log 8 9 10 Detailed physics is still controversial! mass shell Fundamental reason: nuclear burning rate in SnIa Deflagration wave in WD conditions ~T12 !! time steps are at 0, 0.6, 0.79, 0 .91, 1.03, 1.12, 'flame' ~ 1cm thick, White dwarf 1.18, 1.24 sec !! 22 has r~108cm Detailed Yields for a SNIa model Abundances are relative Type Ia Nomoto et a; 1984 to solar We will come back to this later....

23

Type IIs • Collapse of a massive star- the cores mass 'burns' into iron nuclei and has a maximum size determined by the Chandrasekhar limit, ~1.4 M. (see late slides on what this is) • Natural from stellar evolution • Leaves NS or BH or maybe no remnant • Wide range of masses, metallicities, binarity etc make for wide range of properties

Lattimer- http://www.astro.sunysb.edu/lattimer/

AST301/lecture_snns.pdf 24 Type IIs • total "optical" energy ~1049erg. • several solar masses ejected at ~1%c • •The kinetic energy ~1051erg

Collapse of massive star to a SN- central density reaches ~3x1014 gm/cm3- several times that of nuclear density

25

Type II Progenitors • In a few cases HST has directly observed the progenitor - has to be Progenitor of SN II 2008bk 5 very luminous ~10 L¤to detect

before

after

26 Elias- Type II Progenitors • In nearby galaxies HST data can constrain the age of the stars near to (50pc)supernova remnants • The most massive stars have shortest lives and explode 'first' – the mass of the oldest living star provides a lower bound to the mass of the star that exploded as a type II SN Estimated mass of progenitor in nearby galaxies 27

Energy Release in Supernovae • Basic idea • Once the core density has reached 1017 -1018 kg m-3 , further collapse impeded by nucleons resistance to compression • Shock waves form, collapse => explosion, sphere of nuclear matter bounces back.

28 Types II/Ib/Ic Core-Collapse of Massive Progenitor TYPE II Supernova Explosion

• Massive progenitor core forms or black hole or perhaps nothing left

• Explosive nucleosynthesis products near core (Si and Fe) plus hydrostatically formed outer layers (O, Ne) are expelled

Initially in core-collapse supernovae (type II) the energy comes from the gravitational energy freed in the collapse- later times from29 radioactive decay

Types II/Ib/Ic Core- Collapse of Massive TYPE II Supernova Explosion Progenitor

• Most of the explosion energy is carried away by neutrinos- • Detection of neutrinos from SN 1987A confirmed basic physics Nobel prize 2002 (Cardall astro-ph 0701831)

• Uncertain explosion mechanism details involve neutrinos, probably large- scale shock instabilities, rotation, possibly magnetic Initially in core-collapse supernovae (type II) the fields energy comes from the gravitational energy freed in the collapse- later times from30 radioactive decay • Mass motion ~1051 2 ergs (~M¤v )ejecta

– SNII M=4M¤ vejecta=5000km/sec – Neutrino luminosity is ~3x1053 ergs 2 (0.15M¤c ) photon luminosity ~1049

Evolution of a massive star from core collapse to NS 31

SNII Explosions- Not Spherical Cows

Wongwathanarat et al. 2015 20 and 15 M¤ explosions ~1 day after the explosion

32 STOP • What are 4 differences between type Ia and II supernova • 1 item per group- I will call on the groups randomly and no repetitions!

33

In massive stars, nucleosynthesis by fusion of lighter elements into heavier ones via sequential hydrostatic burning processes called helium burning, burning, oxygen burning, and burning, in which the ashes of one nuclear fuel become, after compressional heating, the fuel for the subsequent burning stage.

During hydrostatic burning these fuels synthesize overwhelmingly the alpha-nucleus (A = 2Z) products.

And so the type II SN ejects the previously made elements -some heavier elements are made in the explosion (zinc, silver, tin, gold, mercury, lead and uranium etc-)

34 Explosive Nucleosynthesis- Type IIs Nuclear processing as the supernova propagates through the star (see Arnett 1996) 'α' products C burning produces O, Ne, Mg, etc T ~ 2 x 109 K Ne burning produces O, Mg, etc T ~ 2.3 x 109 K O burning produces Si, S, Ar, Ca, etc T ~ 3.5 x 109 K Si burning produces Fe, Si, S, Ca, etc T ~ 5 x 109 K

stops at Fe, sort of 35

Binding energy of Nuclei - why stellar burning stops generating energy

A=total no. nucleons Change from X to Y emits Z=total no. energy since Y is more E = tightly bound per nucleon b than X. This is a function of nucleon mass Fusion Fission binding energy per nucleon binding per energy A X Y Fe Y X [email protected] http://www.mssl.ucl.ac.uk/ 36 SNIIa

On the way to explosion • Oxygen burning goes very fast (~2 weeks) Si even faster ~1 day. • Photon energy leaks out very slowly (cross sections for interaction very large), neutrinos escape rapidly (during final collapse opacity high even for neutrinos)- • not understood how the burst of neutrinos transfers its energy to the rest of the star producing the shock wave which causes the star to explode- – only 1% of the energy needs to be transferred to produce an explosion, but explaining how that one percent of transfer occurs has proven extremely difficult

37

SNII

• Once Fe core reaches Chandrasekar mass electrons are relativistic, and unstable to . • Core temperature extremely high- elements photo-disintegrate; this lowers increasing runaway (R+B pg 129-130) • Core collapses (v~r) and outer parts of star fall in supersonically • Then things get hideously complicated ...

38 • Present understanding of explosion of massive star (Janka et al 2007) • importance of hydrodynamic instabilities in the supernova core during the very early moments of the explosion

39

SNII Snapshots over the first 0.10- sec

Left side of panel shows velocities

Right side the elements and neutrinos (ν) 40 0.1-0.12 Secs • infall and neutrino burst

41

0.2-10sec • Start of outflow

42